FIG. 1 shows a network 104 that communicatively couples two nodes (e.g., a client or server) 101, 102. The nodes typically have an operating system and application software that runs on the operating system. A transport layer is a networking layer located on each of a pair of the network nodes 101, 102 which is responsible for controlling the flow of information between applications located on each node 101, 102. Currently, a transport layer protocol referred to as Transmission Control Protocol (TCP) is widely utilized for communications that transpire over the Internet.
FIG. 2 shows an amount of data 201 that is representative of the amount of data to be passed from one node to another node over a network. The data 201 may be viewed as an addressed block having a starting address 202 and an ending address 203. In order to ensure that the sending node does not “overflow” the network's capacity, TCP regulates the amount of data allowed on the network.
TCP regulates the amount of data allowed on the network at any given time by limiting the range of addresses that correspond to transmitted data. That is, only a contiguous portion 204 (e.g., from a first address 205 up to a second address 206) of the complete amount of data 201 is allowed on the network at any given time.
The range of in transit addresses (e.g., between addresses 205 and 206 inclusive as seen in FIG. 2) is refered to as the a window 204. Under TCP, new data (e.g., located just after address 206) will not be sent onto the network by the sending node until an earliest portion of data within the window (i.e., just after address 205) is acknowledged by the receiving node. As such, data is sent over the network by effectively sliding the entire window 204 forward (i.e., from left to right as seen in FIG. 2) across the entirety of the data 201.
TCP is designed to rapidly increase the flow of data between the sending and receiving nodes until data begins to be lost on the network or a predetermined flow limit is met. In the former case, TCP lacks sophisticated means for anticipating network congestion or loss. In the later case, the pre-determined limit may be well below the network's capacity. As such, TCP typically presents too much or too little offered load to the network.
Furthermore for either case, should data begin to be lost on the network, TCP “overreacts”. Upon loss, it halts all data flow before resuming data flow (possibly including data that was not lost) at a drastically reduced level. As such, the flow TCP offers to the network tends to oscillate between network over utilization and network under utilization. Further still, the oscillation tends to worsen as the number of TCP flows traversing the network increases.
Lastly, for network communications between a client node (also referred to as a client) and a server node (also referred to as a server), TCP tends to place to omuch processing burden on the server. For example, under TCP the server controls and keeps track of the window size and data addressing discussed above. As a result, if the server has to support a large number of communication session with various clients, the server's resources become strained trying to control each session.